The invention relates generally to an apparatus and method to track a fluid with a wireless tracking device entrained in the fluid.
It can be desirable to track a fluid in a wellbore, e.g., a wellbore in a formation for the recovery of hydrocarbons. Tracking a fluid can include determining the location of a fluid loss zone and/or the location of a fluid itself, e.g., drilling mud, cement, etc., in the wellbore. One way of identifying a possible location of a loss zone, e.g., lost circulation, is to use a noise log, which measures any increase in movement or activity in a wellbore based on the change in tone or volume in the noise of flowing fluid at a certain depth, using specialized logging tools. Another method of identifying a possible location of a loss zone, as well as evaluating a cement or hydraulic fracture treatment, is to use a temperature log, which measures changes and/or variance in temperature, again using specialized logging equipment. Both of these methods can be imprecise and/or fail their intended purpose.
A tracer which has been used for decades is a radioactive isotope in, most commonly, powdered form and placed in a carrier fluid and pumped down hole. The location of the radioactivity is searched, for example, to determine an exit point or concentration somewhere in the wellbore. In the U.S., for example, stringent Occupational Safety & Health Administration (OSHA) and/or environmental regulations can impede use of radioactive tracers.